Can Field Data and Science Save the Bornean Orang-utan?

Fifteen years ago, when I was living in Sarawak, Malaysian Borneo, I would occasionally be privileged enough to be able to watch wild Bornean orang-utans in the rain forest. Every time it was a thrill. Orang-utans are the only great apes occurring in Asia; indeed, the only ones outside Africa.

Tragically, the IUCN Red List of Threatened Species, that treasure trove of accurate scientific information on the status of the world’s species, has just declared the Bornean orang-utan to be Critically Endangered – just one step away from Extinct in the Wild. This is especially shocking since orang-utans historically occurred throughout the island of Borneo – at 287,000 square miles, the third largest island in the world (larger than France, Belgium, and the Netherlands combined).

Bornean orang-utan. Image: Daniel Kong/WCS.

While orang-utans hold the rank of largest arboreal animal in the world and sport bright red coats, they can be amazingly difficult to see in the dense forest! The glimpse of a hairy red arm, the rustling of branches, or the glance of the clearly-intelligent eyes watching you, are often the only signs of a 150 pound animal moving around immediately overhead!

Unlike other great apes, orang-utans are primarily solitary, and population densities are naturally low, often only about four animals per square mile, so tracking them down is especially challenging. However, each adult orang-utan makes a nest each night, bending together branches and leaves to constuct a comfy bed. Those large leafy nests in the tree canopy are a sure sign that orang-utans are in the area. The occasional long-distance call from an adult male is an added thrill, even without seeing any animals.

So why have orang-utans become so threatened? The first reason is loss of their rain forest habitat, which has been chipped away at the edges with the spread of housing and small-scale local agriculture. More recently, heavy habitat loss has stemmed from large scale clearance for industrial agriculture plantations, especially oil palm. This activity has been most pronounced in the lowlands where orang-utans mainly occur. In the past half-century, more than 60 percent of this forest has been cleared.

On top of that are the notorious fires linked to El Niño — climatic events that have been increasing in frequency and severity in recent years. Especially problematic is that large areas of Borneo’s forests grow on deep flooded peat soils. When the forest is cleared, the peat dries out and can burn, with fires often continuing underground for years.

Slash and burn land clearing has led to long-burning peat fires in Borneo and elsewhere. NASA image by Adam Voiland (NASA Earth Observatory) and Jeff Schmaltz (LANCE MODIS Rapid Response)

I was in Sarawak during the massive 1997-98 fires in Indonesian Borneo, when the resulting smoke caused the declaration of a state of emergency. Even hundreds of miles away, I witnessed the closure of schools, government offices, ports, and air fields due to poisonous air and low visibility.

More than 1,500 square miles of peatland forest burned during that time, leading to the loss of an estimated 8,000 orang-utans.

If that were not enough, orang-utans are also threatened by hunting. Even though they are one of our closest relatives and protected by traditional taboos in some areas, orang-utans are hunted for food across much of Borneo. Females are shot to collect their dependent young for the illegal pet trade. Because orang-utans are the slowest breeding mammals in the world, producing only one offspring every four to eight years, a loss of even 1 percent of the females in a population can lead to local extinction.

Subsequent visits to the island in recent years have convinced me that when it comes to the Bornean orang-utan, field data and science can combine to raise a large red flag about a huge problem. The reclusive nature of the animals, and the seemingly large areas of their range, could otherwise deceive us into overlooking a problem until it’s too late. And if we could overlook it for such a large and easily-recognized animal as an orang-utan, how much more might we do so for other less conspicuous and familiar species!

For the Bornean orang-utan, this must be a clarion call for action. We know what we have to do: ensure that large areas of forest are protected and that illegal hunting of, and trade in, these gravely threatened great apes is stopped.

In the State of Sarawak, the current Chief Minister, Datuk Patinggi Tan Sri Adenan Satem, has declared that all forests containing orang-utan populations must be protected. If this can be achieved, and then replicated across Borneo, it would provide a beacon of hope for the island’s iconic orang-utans, so that generations to come can still have the thrill of seeing a gentle hairy red giant peering down at them from the forest canopy above.